Sea urchins reveal promising carbon capture alternative

The sea urchin has revealed a way to ceaply and quickly convert CO2 into calcium carbonate (Photo: Shutterstock)

Carbon capture and sequestration in underground reservoirs isn’t the most practical or cost effective way to reduce atmospheric CO2 levels. It would be much simpler if CO2 could be quickly and cheaply converted into a harmless, solid mineral before it is released into the atmosphere. A team from the U.K.’s Newcastle University may have stumbled across a way to achieve this thanks to the humble sea urchin.

As part of their research into what happens when CO2 reacts with water – known as the carbonic acid reaction – the researchers were looking for a catalyst to speed up the process. By chance, Dr Lidija Šiller, a physicist and Reader in Nanoscale Technology at Newcastle University, was looking at the way in which organisms absorb CO2 into their skeletons at the same time.

Dr Šiller was looking specifically at the sea urchin, which converts CO2 into calcium carbonate to form its endoskeleton. “When we analyzed the surface of the urchin larvae we found a high concentration of nickel on their exoskeleton,” says Dr Šiller. “Taking nickel nanoparticles which have a large surface area, we added them to our carbonic acid test and the result was the complete removal of CO2.”

Gaurav Bhaduri, lead author on the paper and a PhD student in Newcastle University’s School of Chemical Engineering and Advanced Materials points out the nickel catalyst offers advantages over other catalysts used to convert CO2 into calcium carbonate or magnesium carbonate, such as the enzyme carbonic anhydrase.

“The enzyme is inactive in acid conditions and since one of the products of the reaction is carbonic acid, this means the enzyme is only effective for a very short time and also makes the process very expensive,” he said. “The beauty of a Nickel catalyst is that it carries on working regardless of the pH and because of its magnetic properties it can be re-captured and re-used time and time again. It’s also very cheap – 1,000 times cheaper than the enzyme. And the by-product – the carbonate – is useful and not damaging to the environment.”

The research team developed a process to capture CO2 from waste gas by passing it directly from a chimney top through a water column rich in nickel nanoparticles. The solid calcium carbonate can then be recovered at the bottom of the column.

The researchers say their discovery could provide big CO2 emitters, such as power stations and chemical processing plants, with a cheap way to capture and store their waste CO2 before it is released into the atmosphere. Since calcium carbonate is already used to make cement and other building materials, the material can also be put to good use.

“Our process would not work in every situation – it couldn’t be fitted to the back of a car, for example – but it is an effective, cheap solution that could be available world-wide to some of our most polluting industries and have a significant impact on the reduction of atmospheric CO2,” said Dr Šiller.

The Newcastle University team has patented the process and is looking for investors to develop it further. Their work appears in the journal Catalysis Science & Technology.